Personally, I wouldn't get a TV Tuner card.. Why go back to Analog and tuners when every great 3D Card these days has a VIVO (Video in Video out) version. You can hook up your DIGITAL cable / sat box to it through an S-Video connector, and just put the cable box next (or under) your monitor.
You can use Windows XP Media center edition to control it, view and record, or you can buy a simple program like WinDVR -
http://www.intervideo.com/jsp/WinDVR_Profile.jsp
That will just show you what the video card is getting.
I've been doing it for years now... works like a charm.
This way you can keep working on your PC, and just have a little window on the corner with TV on it!